1. Technical Field
The present invention relates to a cleaning apparatus, especially to a cleaning apparatus for printed circuit boards.
2. Discussion of Related Art
Recently, as the electronic appliances are becoming smaller in size and diversified in function, printed circuit boards (PCBs) widely used in such electronic appliances are required to have higher circuit density and reliability.
Usually, a chemical etching process is used for etching a conductive pattern on a copper clad laminate (CCL) as described below. First, a photoresist layer is applied on the CCL by screen printing method. Second, the CCL is driven to pass through an etching bath by a feed roller, thereby an etchant is sprayed simultaneously and evenly onto both an upper surface and a bottom surface of the CCL by a number of spray nozzles. As a result, the copper layer uncovered by the photoresist layer is etched and a conductive pattern is formed on the copper layer. In order to obtain a multilayer PCB, additional CCLs will be applied on the etched CCL and then through holes may be formed using a drilling method or laser ablation method. After that, through holes are plated a copper layer thereon. Finally, the chemical etching process is repeated so as to form conductive patterns on the outer CCLs.
Various dust or debris produced in the above mentioned method are likely to cling on the CCLs. Such dust or debris may affect the quality of the CCLs. For example, referring to FIG. 13, a piece of debris of adherence layer clings on a copper layer. The debris acts as a protective layer when the copper layer is etched. As a result, the area under the debris, which is set to be etched, is not etched. This will cause short circuit between the conductive line 13 and 14. Therefore, CCLs must be cleaned prior to perform steps such as etching on the CCLs. Accordingly, there is a desire to develop a cleaning apparatus for cleaning CCLs.